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Mine filling and tunnel spraying projects pose high requirements on the rheological properties of cement-based materials.The types, conditions of fine sands and the exposed environment have significant effects on the rheological properties.In this light, this paper uses coal gangue sand instead of quartz sand as the fine aggregate of cement-based material and investigates the effect of temperature and aggregate prewetting on the rheological properties of mortar and its mechanism.Results show that the shear stress-shear rate relationship of coal gangue mortar conforms to the characteristics of Herschel-Bulkley(H-B)model, with higher rheological index(higher than 1)and higher consistency than that of quartz sand mortar.The apparent viscosity of coal gangue mortar decreases with increasing temperature, but the effect of aggregate prewetting is not significant.The yield stress of coal gangue mortar at 30 ℃ is 2.99 Pa, 1.45 times higher than that at 10 ℃, and 2.13 times higher after prewetting.The thixotropic ring area of coal gangue mortar is higher than that of quartz sand mortar, and the thixotropic ring area of pre-wetting coal gangue mortar is 398.4 Pa/s, while that of dry coal gangue mortar is 283.3 Pa/s.The obtained results are expected to provide evidence for the rational utilization of coal gangue sand and the design and preparation of rheological materials served in complex environment.

Using aeolian sand(AS)for backfilling can realize local material extraction and turn waste into treasurethe, and realize coordination of green mining and AS control.The AS filling mining is mainly applied to the backfilling of goaf under Highway, backfilling mining of coal mine and metal mine.Grouting and sand injection in the goaf, solid backfilling mining, high water backfilling mining and cemented backfilling mining are developed.Long wall backfilling mining, strip backfilling mining and roadway backfilling mining are adopted.The research on the properties of cemented AS backfilling materials focused on slurry fluidity and backfill strength.In this paper, the rheological properties of cemented AS slurry with different proportions and curing times are analyzed, and cemented AS backfills are toughened by using polypropylene fiber.The results showed that the rheological parameters of cemented AS slurry increased with the curing time, and the addition of fiber significantly improved the brittleness characteristics of cemented AS backfills.

Knowledge graph is an indispensable part of cognitive intelligence research.Aiming at the problem that the traditional analysis method of stope mine pressure hazard events has insufficient expression of the stress time and space evolution process and the relationship between hazard evolution and risk prevention and control in the coal mining process, this paper proposes a knowledge graph representation method that based on the entire life cycle of stope for mining pressure hazard events.Firstly, from the perspective of geological disasters, the dynamic characteristics of stress and distribution in stope were analyzed.The dynamic correlation of various nodes in mine pressure geological disasters was established, and a knowledge graph representation method for mine pressure geological disasters considering spatiotemporal processes was proposed.Secondly, from the perspective of accidents, the evolution of hazard and the process of risk prevention and control in mine pressure accidents were analyzed.The evolution of hazard and preventive measures were integrated into the knowledge graph representation model.Finally, Neo4j was used to build the knowledge graph of mine pressure hazard events.The results indicate that the knowledge graph constructed based on this representation method not only depicts the spatiotemporal evolution processes of different objects in disaster events but also describes the coupling evolution process of hazards and corresponding risk prevention and control measures.This provides an intelligent research pathway for the prevention and control of mining pressure hazards in intelligent mining.

China's intelligent mine construction is still in the early stage of development, which is seriously constrained by data trust problems such as low credibility of mine data, lack of trust mechanism in the data sharing process and the risk of data security and privacy leakage.To this end, this paper proposes an intelligent mine data trust model by drawing on the holistic approach to national security.Specifically, this study 1) offered a working definition of this model and proposed its underlying conceptions; 2) designed its technical architecture and analyzed the core technologies involved; 3) proposed the implementation strategies of the intelligent mine data trust model based on blockchain technology.This may lay the foundation for blockchain technology to empower intelligent mines and comprehensively enhance its efficiency and productivity, thus promoting the high-quality development of the coal industry.

The application of digital twin technology in the field of intelligent mining needs to face many complex and special technological breakthroughs. This article elaborates on the applicability of digital twins in the field of intelligent mining, and summarizes the research and application status of digital twin technology in coal mine safety, production, and operation management. In terms of coal mine safety management, digital twin technology is mainly applied in disaster warning, risk control, disaster rescue, etc. In terms of coal mine production, digital twin technology is mainly applied in the overall mining working face area, monitoring and control of single machine mechanical equipment status, and predictive maintenance of mechanical equipment. Starting from five dimensions: physical entity, virtual entity, connection interaction, digital twin data, and functional services, this paper explores the key common problems that urgently need to be solved in the field of intelligent mining. The physical entity dimension needs to focus on breaking through the research and development of comprehensive perception and control equipment. The virtual entity dimension needs to conduct in-depth research on physical, behavioral, and rule models. The connection interaction dimension needs to tackle key technologies for underground 5G network transmission in coal mines. The twin data dimension needs to solve problems such as high-performance computing. The functional service dimension needs to develop simulation software and artificial intelligence algorithms to better adapt to the on-site environment. This article looks forward to the development trend of digital twin technology in the field of intelligent mining from the aspects of disaster prevention design, production system design, geological environment prediction in the planning, development, and construction stages of mines, disaster warning and prevention, optimization of production scheduling decisions, and full life cycle management of production equipment in the production and operation stage of mines. It is believed that fine twinning should be carried out for key components or equipment, core links, important or dangerous places, areas, etc.

Under the trend of deep mining of coal resources, the problem of high temperature heat damage in mines is becoming increasingly serious, the heat source that causes high temperature heat damage in mines is actually sustainably used geothermal energy, extracting and utilizing geothermal energy from deep mines while mining coal is an innovative way to build green mines and reduce mine carbon dioxide emission. This paper summarizes the current situation of deep mineral and geothermal energy collaborative exploration at China and abroad, analyzes the feasibility in terms of processes and key equipment and finally proposes a system of coal-geothermal collaborative exploration. The system adopts closed cycle mode, including ground heat utilization system and underground extracting system, drilling horizontal holes and installing coaxial casing heat exchangers at the coal to extract the heat, and utilization of the extracted low-grade geothermal energy through the heat pump on ground. Adhering to the principle of “mining heat first and then mining” in terms of time and space coordination, the thermal mining face is divided in front of the mining work in advance, and two modes of sequential and alternating thermal mining are proposed to ensure that the thermal mining process does not interfere with the coal mining process. Analyzed key technologies including spatial collaborative design, coal seam drilling, efficient heat extraction, and intelligent monitoring and control. Conducted underground spatial collaborative design for coal mining and geothermal energy extraction, proposed a coaxial casing heat exchanger layout process based on coal seam water injection. Multiple combinations of quick assembly coaxial casing heat exchangers can be used to achieve efficient heat extraction. Building an intelligent monitoring and control platform and proposed relevant optimization models, building a heat extraction calculation model and propose an intelligent control heat extraction method. Simplify the heat transfer process of coal formations, construct a heat transfer model for heat extraction from coal to calculate and evaluate the heat capacity of the mining face based on its actual situation and the outlet airflow parameters. According to the heat transfer model, the initial temperature of coal, the coal transportation volume, and the outlet air flow temperature through mining face are the key parameters that determine the heat extraction from the coal. The heat extraction is the maximum when the moisture content of the air flow of the working face remains unchanged and the equivalent temperature of the air flow at the outlet of the working face is not higher than 28 ℃. The application of this system will converting heat damage of deep mine to useful resources, which not only solves the problem of heat damage of coal mining, but also realizes the comprehensive utilization of geothermal energy in deep mine.

In order to explore the effects of pore size, aromatic lamellar stacking degree, aromatic lamellar ductility, gas temperature and gas pressure on the competitive adsorption of CH4 and CO2, the No.3 coal from Jincheng mining area was taken as the research object. The adsorption process of binary mixed gas of CH4 and CO2 in coal under different temperatures, pressures, pore diameters, aromatic lamellar stacking degrees and aromatic lamellar ductility was studied. The microstructure of coal was tested and analyzed based on industrial analysis and X-ray diffraction experiments. Molecular simulation of the process of gas mixture adsorption in coal using the Grand Canonical Monte Carlo (GCMC) method. The results shown that, the increase of gas pressure was favorable for adsorption, and the adsorption capacity of CO2 was close to saturation at a pressure of 5 MPa. The increase of temperature led to a decrease in the maximum adsorption capacity and adsorption heat of CO2 in coal. The increase of pore size led to the increase of CH4 adsorption capacity in coal, with the fastest increase in CH4 adsorption occurred when pore size increased from 1 nm to 2 nm. With the increase of aromatic lamellar stacking degree, the number of gas molecules adsorbed in coal did not change significantly, but CO2 adsorption capacity of per unit mass in coal decreased rapidly, and the CH4 adsorption capacity decreased slightly. With the increase of aromatic lamellar ductility, the number of CH4 molecules adsorbed in coal increased slowly and the number of CO2 molecules adsorbed increased rapidly, and the change of the two gases adsorption capacity in coal per unit mass was not significant. From the perspective of adsorption capacity and adsorption heat, CO2 is in a dominant position in the competitive adsorption process, so injecting CO2 into coal seam can effectively displace CH4. The results of this paper strengthened the molecular understanding of the adsorption of binary mixed gas of CH4 and CO2, which can lay a theoretical foundation for the enhancement of coalbed methane extraction by CO2 injection.

Aiming at the problem of high leakage rate and false alarm rate of traditional statistical methods for abnormal fluctuation in sensor monitoring data caused by dampers opening and closing, a SSA-LSTM wind speed abnormal fluctuation detection method based on the combination of Singular Spectrum Analysis (SSA) and Long and Short-Term Memory Neural Network (LSTM) was proposed by mining the data features in the time-series data in the wind speed sensors. Firstly, SSA was used to pre-process the wind speed sensor monitoring data, and the wind speed data was decomposed into trend component, periodic component and noise component. The data noise generated by turbulent pulsation was removed via reorganizing the trend component and noise component. The LSTM parameters was then optimized, and the optimized LSTM model was used to predict the pre-processed data and obtain the reconstructed wind speed. Finally, the anomaly fraction of the monitored wind speed and reconstructed wind speed was calculated by using the logarithmic probability density function. Anomaly detection for monitoring wind speed was performed by calculating the threshold set value of training set data samples. The experimental results shown that, the removing effect for the data noise generated by turbulence pulsation via SSA was better. Removing the noise component without affecting the data fluctuation was helpful in improving the wind speed reconstruction effect and the anomaly detection accuracy. LSTM can correctly reconstruct the small amplitude wave due to turbulence pulsation without anomalous fluctuation and fits well with the actual data. The reconstruction of abnormal fluctuation segment based on historical fluctuation trend when there was abnormal fluctuation can effectively improve the accuracy of anomaly detection. Through comparative analysis, the reconstruction effect of proposed method in this paper was better than ARIMA, BP and CNN models, with an anomaly detection accuracy of 99.2% and an F1-Score of 0.97, which verified the reliability of the proposed method. The method proposed in the paper has important application value in detecting the abnormal fluctuation of wind speed caused by the opening and closing of dampers.

Studying the interaction between coal slime and flotation agents will be the hot and difficult point of flotation process strengthening. In view of the strong hydrophilic chemical structure characteristics of the surface of difficult flotation coal, this paper introduces the bio-pharmaceutical induced fit effect into the study of the interaction of polar collectors in difficult flotation coal flotation. In this paper, 3D coal molecular structure was optimized and constructed according to the results of coal sample properties. Protomol technology was used to search and represent the active pockets of coal molecules, and the optimal conformation of molecular butt between polar collector and difficult floating coal was searched in the active pockets. According to the binding energy of the optimal conformation of the interaction between polar chemicals and coal molecules, the correspondence between the molecular docking results, induced fit effect and the flotation results was analyzed. The molecular docking results and the recovery rates of refractory coal combustible are both lauryl alcohol< lauraldehyde< methyl laurate, The recovery rate of flotation fuels is positively correlated with the absolute value of molecular docking binding energy and the molecular induced binding effect of coal, which revealed the guiding effect of molecular docking on flotation reagent screening. According to the molecular docking configuration, the differences in binding energy can be attributed to the differences of π-CH interaction and steric hindrance. Furthermore, the three-dimensional space of pharmaceutical molecules was fixed and the induced fit effect between three polar collectors and coal molecules was explored by molecular mechanics simulation. It was found that methyl laurate and the active region of coal molecules could generate greater interaction, and the active region of coal molecules had stronger induction effect and inclusion of methyl laurate, so it had better effect in the flotation process. The application of molecular docking and induced fit effect technology in the field of biomedicine to the field of flotation reagents can provide technical approaches and scientific guidance for the rapid screening of flotation collectors.

The coal industry is the ballast stone and stabilizer that supports the rapid development of China’s economy and society and ensures national energy security. It also undertakes the mission of ensuring energy supply and supporting the stable development of new energy. At present, the high-quality development of China’s coal industry has achieved some staged results, with remarkable achievements in energy supply, the continuous optimization of industrial structure, the significant improvement of scientific and technological innovation capabilities, and the continuous advance of green development and clean and efficient utilization. However, the current development level of the coal industry is far from meeting the national needs of Chinese-style modernization. The sustainable development is restricted by multiple factors. The digital technology and coal development and utilization have not yet been deeply integrated. The intelligent construction is still in the demonstration and cultivation stage. The green development is unbalanced and contradictory and prominent. The transformation and upgrading of the coal industry still has a long way to go. In view of the current development status and challenges of the coal industry, this paper proposes a synergistic development mode of digitalization, intelligentization and greenization (three -izations), clarifies the core connotation of new-quality coal productivity, constructs the overall framework of the synergistic development of new-quality coal productivity, and expounds the technical path for the transformation of the innovative allocation of production factors by digitalization, the breakthrough of key technologies led by intelligentization, and the deep transformation of traditional industries by greenization, i.e., by these three factors to generate new-quality coal productivity. Six major technical systems are proposed: through the research and development of the technical system of efficient data collection and in-depth governance of the whole industry chain, the data barriers among coal production, transportation, storage, marketing and use of the whole process are removed. Through the research and development of the knowledge map and intelligent decision-making and control technological system of the coal industry, the correlation relationship and value of the upstream and downstream business scenarios of the coal industry are deeply explored, so as to lay the foundation for the independent decision-making and intelligent control of the whole process of coal production and utilization. Also, the research should be carried out in terms of the intelligent-green-efficient development technological system of coal resources, the technical system of collaborative guarantee of safety in the coal industry, the technical system of ecological intelligent monitoring-early warning-restoration in mining areas, and the technical system of flexible development and clean and low-carbon utilization of coal, so as to realize the synergistic development of the whole industrial chain and the whole process of coal development and utilization, cultivate and form a new-quality coal productivity, and bring some fundamental changes and improvements to the overall image of the coal industry.

The acceleration of the energy transition is driven by current geopolitical conflicts and climate and environmental challenges. It is crucial for China to construct a new energy system adapting to these changing circumstances for the sustainability, security, and stability of the energy supply system. At present, fossil fuels still dominate the China’s energy demand. There are energy security issues due to lacking oil and gas resources, and new energy technologies. China will still maintain a high dependence on coal energy in short term, consequently, prompting the clean and efficient conversion of coal is vital for developing a new energy system. In this paper, the specific connotations and develop direction of the new energy system are identified, and then the development status, opportunities and challenges of the China’s coal chemical industry in the new era are presented, also the suggestions for improving the technology of clean and efficient coal conversion and the future development of coal chemical industry are put forward. The new era has endowed the new energy system with more connotations, that is the future energy system should be characterized by “safe and efficient, clean and low-carbon, diverse and synergistic, and intelligent and accessible”. In addition, the new era will put forward higher requirements for the clean and efficient development of the coal industry.Although China has made significant achievements in the clean and efficient conversion of coal, the key technologies still need some breakthroughs.Combining the systematic understanding of the relationship between the transformation and development of the coal industry and the “dual carbon” goals, and in the context of the construction of a new energy system, the promotion of clean and efficient coal conversion is of great significance for social and economic development and helping to achieve the “dual carbon” goals. The key lies in strengthening the basic research of relevant disciplines and specialties in this field, as well as the innovative development of clean and efficient coal conversion technologies.

With the gradual development of coal mining into deep strata, the large deformation failure and strong dynamic impact disasters of surrounding rock caused by deep mining are becoming more and more serious. Under the complex geomechanical conditions including high ground stress, high ground temperature, high permeability, strong mining disturbance, strong rheology, and multi-field coupling, the stress field characteristics, rock fragmentation properties, strata movement and energy accumulation and release laws of deep mining areas are significantly different compared with those in shallow mining areas. In response to the rock mechanics issues in deep mining, this paper discusses the research progress made by the authors and team in three aspects: deep coal mining methods, failure mechanism and control of surrounding rock in deep roadway, and deep thermal disaster and geothermal utilization. The main results are as follows: ① the theory of balanced mining and the 110/N00 methodology for achieving balanced mining were proposed and applied in kilometer deep mines. ② The deep shaft construction mode with non-uniform pressure was proposed, and a SAP system to realize the stable lifting was developed. A mine construction method which can greatly reduce the roadway quantities and improve the coal recovery rate was invented. ③ Multiple experimental systems suitable for studying the macroscopic failure of deep soft rock under the effects of water, high temperature, high pressure, structural effects, multi-field coupling were developed. A supercomputing system capable of performing microscopic-level calculations was established. Based on the experimental results, the mechanism of large-scale deformation and failure of deep soft rock and its multi-scale mechanical properties were revealed. ④ An experimental system for simulating deep shock-type and strain-type rock bursts was built, and it was revealed that the rock burst is a nonlinear dynamic behavior in which energy is instantaneously released along the excavation-free surface. ⑤ The theory of excavation compensation support for deep roadway was proposed, and a NPR materials with extraordinary mechanical properties such as high constant resistance, high elongation, strong energy absorption, and impact resistance were invented. ⑥ A thermodynamic experimental system which can simulate deep high temperature, high humidity, and high-pressure environments was constructed, and a high temperature exchange machinery system (HEMS) for heat disaster treatment and heat source resource utilization was established. The above research achievements have been applied in the field of deep mining and can provide guidance for the complex rock mechanics problems faced by deep mining.

This paper analyzes the current situation and existing problems of coal roadway driving technologies and equipment, introduces the new mode, technology, equipment of coal roadway rapid driving with integrated drilling and anchoring and its underground applications. The bolting technologies and equipment with integrated drilling and anchoring are developed which include the integrated drilling and anchoring bolt, pumpable resin, drilling boom and drill rig as well as bolts cartridge with integrated drilling and anchoring, pump unit and intelligence control system. The new technology simplifies the traditional six-step rock bolting process to one continuous step. Rock bolting can be realized automatically by pressing button once and the operation time for installing a single bolt can be reduced from 5 to 6 minutes to 3 minutes. The technologies and equipment of automatic spraying support are developed which include high-strength, rapid setting, and deformable surface supporting spraying materials with a tensile strength exceeding 9 MPa, elongation at break exceeding 100%, and a bonding strength exceeding 3 MPa. The spraying system with 6-degree-of-freedom manipulator is developed which can automatically and rapidly spray during roadway driving. The dynamic monitoring technology and system for roadway surrounding rock deformation are developed during driving which can achieve a surface deformation monitoring of roadway in environments with dust, multiple interference, and low illumination. The monitoring accuracy can meet the requirements of the surrounding rock stability evaluation. A new partitioned parallel collaborative rapid driving mode of excavation, spraying, bolting and transport is proposed and a complete set of roadway rapid driving equipment with integrated drilling and anchoring is developed. The displacement and stability of the surrounding rock during the driving process at the Caojiatan Coal Mine in Shaanxi Province are monitored. In terms of time, more than 80% of the surrounding rock displacement had already occurred in 2 to 3 hours after the excavation of the roadway. In terms of space, more than 90% of the surrounding rock displacement had already occurred at a distance equivalent to twice the width of the roadway from the excavation face. Therefore, the roadway surrounding rock displacement caused by rapid driving can be completed in a short time, requiring timely and rapid support. The nearly 6 000 m roadway driving project has been completed in the 10-metre-extra-high fully mechanized mining face of the Caojiatan Coal Mine, and over 60 000 bolts with integrated drilling and anchoring are installed. The time for installing a single bolt, the number of supporting workers, and the labor intensity of workers have been significantly reduced. The driving speed, efficiency, and automation level have been significantly improved. The displacement of the experimental roadway roof is small. The roadway surrounding rock stability is good as well as the support effect. The coal roadway rapid driving technology and equipment with integrated drilling and anchoring have achieved a success in underground field test. It has the ability to achieve a monthly driving footage of 1500 to 2000 m for ultra-large cross-section coal roadways.

Under the background of “dual-carbon” goal and current technological conditions, coal, waste and carbon constitute an impossible triangle in the coal industry which severely constrains its green, low-carbon, and sustainable development. Adhering to the principles of treating waste with waste and returning the waste to where it comes from, with a focus on the three-dimensional perspectives of damage reduction in coal mining, the functional utilization of mining waste, and low-carbon disposal of carbon in mining industry, this paper explores a synergistic development path for coal, waste and carbon. It provides a comprehensive solution to unravel the impossible triangle and promote the overall green, low-carbon development of coal industry. The specific contributions of this work include: ① Clarifying the scientific connotation of damage reduction in coal mining, the spatial combination characteristics of aquifers in the ecologically fragile areas, the movement patterns of overlying strata under the application of coal mining damage reduction techniques, and the surface deformation patterns resulting from overlying strata damage; proposing the original technologies of drilling-backfilling-retention for section pillar extraction, narrow strip mining with backfill, and backfilling behind fully-mechanized longwall face aiming to address the challenges posed by damage reduction mining; ② Interpreting the scientific connotation of functional utilization for mining waste; clarifying the scientific issues related to the modification methods and mechanisms of magnesium-coal-based solid waste material, the mechanisms of synergistic interactions among diverse solid wastes, and the properties control of total solid waste backfilling materials. These efforts have led to the establishment of a key technological system for the functional utilization of solid waste, with a core focus on the modification of solid waste raw materials, the development of solid waste-based cementitious materials, and the preparation of solid waste based backfilling materials; ③ Elucidating the scientific connotation of low-carbon disposal of carbon with a scientific practical framework and implementation pathway; clarifying some scientific issues related to mineralization material preparation, storage space construction, CO2 storage and control mechanisms, the long-term environmental effects of CO2 storage, and reservoir stability in the low-carbon disposal process of carbon. The scientific issues related to mineralization material preparation, seal space key technologies such as fractured space CO2 storage and CO2 sequestration through coal mine carbon solidification are explicitly defined which results in a new model for achieving a low-carbon CO2 storage in coal mine goaf. Based on the green, low-carbon and sustainable development of coal industry, it is of great significance to collaboratively promote the damage reduction in coal mining, the functional utilization of mining waste, and the low-carbon disposal of carbon. This coordinated effort plays a crucial role in advancing the realization of the dual-carbon goal in the coal industry.

Coal has made important contributions to the industrialization process of human society, and has played a key supporting role in ensuring China’s energy security and stable economic development. Since the mid-19th century, the coal-based fuel of coal, kerosene, gas and coal electricity has gradually entered the era of large-scale use. However, the traditional use of coal produces high carbon emissions, which has become a major problem in energy transition. Facing the development of ecological civilization society, the clean and efficient use of coal is imminent, and the innovation of modern coal-based energy technology is imperative. This paper proposes the definition and connotation of modern coal-based energy technology system, which is defined as the production of low-carbon energy products such as coal-based gas, coal-based oil, coal-based hydrogen and coal-based electricity, and the in-situ absorption of carbon dioxide in mining areas to form a clean and low-carbon energy production system with carbon neutrality. Its technical connotation includes coal-based gas, coal-based oil, coal-based hydrogen, coal-based electricity and dynamic carbon neutrality in mining areas, with a total of 5 technical modules, 19 technical units and 61 key technologies. The modern coal-based energy technology system will play an important role of “one main body, three supports and one breakthrough” in the future new energy system. Coal-based electricity provides the main body of electricity system stability. Coal-based oil supports the China’s oil safety. Coal-based gas supports the China’s gas safety. Coal-based hydrogen plays a supporting role in the development of hydrogen energy in China. The major breakthrough is the dynamic carbon neutral technology of coal-based energy. The paper supposes that when the ratio of non-fossil energy and low-carbon coal-based energy is maintained in the range of 2.5−3.0, coal-based energy, oil and gas and wind, water, nuclear energy can be reasonably integrated to form a new quality energy system with strong complementarity, high reliability and low carbon emissions. Based on the major breakthrough and practical application of modern coal-based energy technology, it is predicted that China’s low-carbon coal-based energy production will reach 1.02 billion −1.46 billion tons of standard coal equivalent (tce) in 2060, equivalent to 18%−24% of the national energy demand, and carbon dioxide emissions will be controlled below 500 million tons. Compared with the current energy transformation planning path based on “de coal” planning, the share of coal in our energy system can increase from 10% to more than 20%, and carbon dioxide emissions will reduce by 50%. At that time, the modern coal-based energy system has great technological innovation significance for China’s energy security and carbon dioxide emission reduction, and helps China to become a country with independent energy supply.

The MILD combustion is a combustion mode that occurs in a moderate or extremely low oxygen environment, combining the advantages of high combustion heat utilization and very low NOx emissions, and is considered by the international combustion field to be one of the cleaner combustion technologies with great potential for application. Since the relevant research began around 1990, the technology for achieving a MILD combustion of gas fuels has been relatively mature, while the research on the MILD combustion mechanism and implementation conditions of solid fuels such as coal powder and biomass is still relatively lacking. Based on the high momentum oxidizer jet, internal recirculation is achieved, eliminating the need for external high-temperature preheating to establish MILD combustion, greatly expanding the application range of MILD combustion. This paper provides an overview of the basic characteristics of MILD powder fuel combustion from the aspects of particle dispersion, heating, ignition, combustion, and pollutants. Due to the uneven dispersion and reaction of particles, the MILD combustion process of carbon-based solid fuels such as coal powder is more complex than that of gas fuels. High speed jet MILD combustion not only increases ignition delay but also expands ignition and reaction zones, requiring systematic research on the characteristics and mechanisms of each combustion stage. This paper introduces the research achievements in the theoretical design and equipment development of solid fuel MILD combustion. It is recommended to improve the existing coal-fired boiler burner, adjust the process parameters to match the MILD combustion mode, increase the residence time of coke particles to improve combustion efficiency, improve combustion stability, and suppress various pollutant emissions, including fine particulate matter, through high-precision numerical simulation. Based on the overall approach of interconnected energy systems, the coupling research between MILD combustion and various new combustion technologies should be promoted, especially strengthening the research on the co-combustion characteristics of coal powder, biomass and hydrogen, ammonia and other combustible gases, and assisting in energy transformation. Exploring the characteristics of turbulent two-phase flow, turbulent interphase heat transfer, and turbulent chemical coupling in the powder MILD combustion is crucial for deepening the understanding of powder MILD combustion. It involves multivariate analysis and high-precision simulation, which will be the focus and difficulty of future research.

The mining industry is a sector aimed at the safe, efficient, green development, and clean, efficient, low-carbon utilization of mineral resources, serving as a foundational industry for economic and social development. In order to make mining development more economical, consider a more comprehensive range of factors, and optimize the design and development processes, in the late 1950s, operations research and computer technology were introduced into mining engineering, giving rise to a new discipline known as mining systems engineering. In its early stages, mining systems engineering primarily focused on the optimization of mining production processes and the use of computers in mine design, excavation planning, information processing, and application software development, with a predominant emphasis on open-pit mining as the research object. In recent years, research in mining systems engineering has closely integrated with big data, artificial intelligence, network technology, and has achieved fruitful results in areas such as mining information network construction, logistics systems, intelligent mining, equipment management, and safety management. This paper provides a detailed exposition of the origin and development process of mining systems engineering, with a chronological narrative based on international conferences on the application of operations research and computers in mining (APCOM), particularly the fifteen national conferences on mining systems engineering that have taken place. It objectively summarizes the developmental process and evolution of research content in mining systems engineering. Using the CNKI database as the data foundation, current research employs cluster analysis to study the publication volume, research objects, and their changes in mining systems engineering over the past 20 years. The future development of mining systems engineering should focus on the integration of systems science thinking with modern mining technology, establishing scientific systems and their boundaries, such as scientific mining systems, mine lifecycle systems, intelligent mine systems, and other eight major systems. The development of mining systems engineering will increasingly emphasize innovation and application in aspects such as digitization, intelligence, sustainable development, informatization, and automation, while continually expanding its application areas to achieve optimized, efficient, green, and low-carbon mining development.

The structure and stress environment of the surrounding rock at the longwall mining area in the steeply dipping coal seam are alienated, and the composition factors and disaster modes of the ”support and surrounding rock” system in the working face are affected. This leads to some frequent safety accidents in the working face, low coal extraction rate, and high roadway excavation rate. This paper analyzes the mining mechanics behavior of surrounding rock of in the steeply dipping coal seam and proposes a technological concept of partial backfill non-pillar mining in the longwall faces of steeply dipping coal seam. During the process of advancing the working face, partial backfill is carried out along the inclined direction in the lower part of the goaf. The filling body not only forms a gob-side roadway with the support effect of the roadway side, but also eliminates the protection coal pillar, achieving a non-pillar mining. At the same time, the length of the filling and compaction area at the lower dip of the working face is increased, enhancing the stability of the ”support and surrounding rock” system of the working face. Based on the characteristics of the longwall mining area in the steeply dipping coal seam, the partial backfill process of the steeply dipping coal seam paste was optimized and determined. And the partial backfill recovery system and mining and filling process in the steeply dipping coal seam were designed. By using a combination of theoretical analysis, simulation experiments, and numerical calculations, the regulatory mechanism of partial backfill on the mechanical behavior of surrounding rock at the longwall mining area in the steeply dipping coal seam was analyzed. The results show that the filling body affects the deformation and failure of the main roof rock beam, as well as the bearing characteristics of the coal and rock mass on the lower side of the mining area. The deformation of the main roof and the roof of the head entry, as well as the constraints on the coal and rock mass on the lower side of the head entry, all decrease with the increase of filling length. In order to prevent the hanging roof disaster in the unfilled area of the goaf, the filling length should not exceed 1/3 of the working face length. The partial backfill body restricts the fracture of the roof in the lower area of the working face, reduces the formation layer of the critical zone of the overlying rock, forms a stable roadway, and reduces the deformation of the surrounding rock gob-side roadway retained. At the same time, the length of the filling area at the lower part of the working face increases, and the length of the unstable area of the middle and upper surrounding rock structures decreases, improving the stability of the ”support and surrounding rock” system. The filling body changes the stress transmission path of the surrounding rock in the mining area, bearing part of the overlying rock load. The side abutment pressure on the lower side of the working face and the front advanced pressure both decrease with the increase of filling length, and the front support pressure in the lower filling area of the working face has the greatest decrease. The stress state of the gob-side roadway and the working face is improved. Technology of partial backfill non-pillar mining in the longwall faces of steeply dipping coal seam has the advantages of effectively improving resource recovery rate, reducing the roadway drivage ratio, alleviating the tension of mining and replacement, and strengthening the stability of the ”support and surrounding rock” system in the working face. It is of great scientific significance for guiding the green, safe, and efficient mining in the steeply dipping coal seam.

The safe, green, efficient and low-carbon coal mining is the common goal of surface coal mines around the world. The development intensity and ecological carrying capacity of surface coal mine resources in China show the reverse development characteristics, and the vulnerable ecological environment areas in northwest China have become the main surface coal production areas, which makes surface coal mining and ecological environment protection become important scientific problems, ecological problems and development problems to be solved urgently. On the basis of the development situation, natural conditions and main influencing factors of surface coal mines, the connotation characteristics and overall structure of realizing the safe-green-efficiency-low-carbon mining of surface coal mines were explained. Aiming at the characteristics of the whole life cycle of pre-mining, mid-mining and post-mining of surface coal mines, in terms of four levels: safe mining technology, green mining technology, efficient mining technology and low-carbon mining technology, this paper puts forward eight key technologies including the time-limited slope control technology, the intelligent early warning decision-making technology, the new mode of transportation link, the ecological construction of mining area, the coordinated mining of adjacent mines, the intelligent mining design, the application of electric mining trucks and the ecological damage reduction at mining sources. The key work and direction of safe-green-high efficiency-low carbon cooperative mining in surface coal mines are clarified. In terms of the measures of safety-green-efficiency-low carbon co-development, regarding strengthening a top-level design, accelerating the distributed implementation, enhancing key researches, promoting personnel training, and improving standards and regulations, the paper proposes the target tasks to be accomplished in different stages in 2025, 2030 and 2035. In the new era, surface coal mines should firmly follow the development path of safe-green-high efficiency-low carbon, and realizes the high-quality development goal of surface coal mines.

With the increasing depth of coal mining, the stability control of surrounding rock in deep roadway has become one of major problems in the mining field, and the effect of surrounding rock control in deep roadway is directly related to the safe production and health of personnel in underground coal mines. The emergence of plastic zone after roadway excavation is the main reason for the stability of the surrounding rock of the roadway. From the perspective of the formation and expansion of the plastic zone, this paper discusses the intrinsic relationship between the roadway damage mode and the distribution of the plastic zone of surrounding rock on the basis of the results from collating and summarizing the existing roadway damage theory and the theory of the plastic zone of surrounding rock. It is believed that the control of the surrounding rock of roadway is essentially the process of controlling the formation and expansion of the plastic zone of surrounding rock. The expansion of the plastic zone of surrounding rock and the control effect of anchor support on the plastic zone of surrounding rock have become an important theoretical basis for the scientific and effective control of surrounding rock in roadway, and based on this, the authors propose the theory and technology for the stability control of surrounding rock in roadway. The results show that the plastic zone is the product of roadway excavation, and the formation and expansion of the plastic zone of surrounding rock is the result of mine pressure. For deep roadways, the appearance of the plastic zone of surrounding rock is inevitable. Scientific control of plastic zone requires a comprehensive understanding of the role played by the plastic zone in roadway surrounding rock. It is necessary to allow the surrounding rock to release the energy in the rock body through plastic failure, but also to prevent the disorderly expansion of the plastic zone. Therefore, in the process of controlling the surrounding rock of roadway, the self-bearing capacity of the surrounding rock should be given a full play as the main focus, and the support intervention should be supplemented. The control of plastic zone of surrounding rock in deep roadway is global and procedural. The control of the plastic zone of the surrounding rock in the whole life of roadway is divided into three stages. By regulating the shape of the plastic zone and inhibiting the expansion of the plastic zone, the stability control of the surrounding rock of deep roadway is realized.

With the gradual transfer of shallow coal mining to deep coal mining in China, the rock burst disasters are becoming an increasingly serious problem. In the process of rock burst mechanism cognition to rock burst prevention engineering, the primary task is to clarify the main factors of rock burst and to identify its risk level. In this paper, four kinds of objective factors i.e., coal rock impact tendency, mining depth, hard roof and geological structure, and three kinds of human factors i.e., coal pillar, goaf and mining unloading effect, were proposed. And the disaster evolution mechanism of each factor was discussed in detail. In terms of objective controlling factors, the impact tendency is the inherent attribute of coal/rock to accumulate deformation energy and induce impact failure. The mining depth is positively correlated with the deformation energy accumulated in the surrounding rock of the roadway, which is an essential condition for the occurrence of rock burst. The impact dynamic load and kinetic energy formed by large-scale hard roof periodic fracture are the 'fuse' to rock burst. The influence of geological structure on rock burst is significant. For fault structure, the two walls will relatively ‘rebound’ under the sudden unloading caused by mining disturbance. And the equivalent elastic modulus of the thinning area of the coal seam becomes larger, and the advanced abutment pressure is distributed in a 'double peak' pattern, which expands the impact influence range. In terms of subjective controlling factors, coal pillar is a high stress concentration area, and its size, dip angle and relative position will directly affect the probability and strength of rock burst. The goaf will induce a sudden release of energy accumulated in the stress concentration area, especially under large mining height and insufficient roof collapse conditions. Mining unloading will lead to the rapid “migration” of the stress concentration area and release a large amount of energy stored in the coal/rock, which is an important external inducement of rock burst. On this basis, the differences of main control factors of rock burst disaster in the main rock burst mining area, such as Xinwen, Luxi, Erdos, Binchang, Xinjiang and Gansu were compared and analyzed. The study emphasized the importance of identifying the main control factors and their influence degree of rock burst from an entire mine, a panel to a working face. Also, it constructed the engineering management path of rock burst from energy-reducing, energy-releasing, energy-damping to energy-resisting.

Based on the green development trend and requirements of China’s coal industry, this paper analyzed the factors that coal mines consider in choosing filling mining methods and the constraints that affect the promotion of filling mining technology. According to the geographical distribution characteristics of different mining areas and the differences in filling demands, four types of priority principles of “protecting the ecological environment, protecting surface buildings, addressing coal gangue and solid waste, and improving economic efficiency” for coal mine filling mining were defined. The ecological mining goal of “building the whole process holographic intelligent ecological mine by adopting filling mining as a regulation tool to protect the ecological environment in coal mines” was put forward. Based on the finite deformation mechanical model of the roof in filling mining, the factors affecting the subsidence of target rocks in filling mining were expounded, and the supporting strength calculation and overburden deformation control equations under three filling engineering modes such as ecological environment protection, ground building protection and gangue treatment were established. In addition, the paper introduced the development status and direction of universal filling technology in coal mines in China, including solid filling of raw gangue waste, modified solid filling, gangue concrete filling, integrated mining-filling-charging, large amount of gangue filling, filling method in thin coal seam, filling method for regional protection, filling method in continuous mining roadway and other filling technologies that meet various needs of coal mines. The material preparation and transportation of different filling technologies, the characteristics of filling process and the adaptive filling equipment were described in detail. In order to realize the intelligent filling of coal mines, a comprehensive data perception system was established, which realized the intelligent process from unit to whole filling working face through spatial planning and filling effect judgment. The sensor network and artificial intelligence algorithm were combined to monitor and control the solid filling process of coal mine in real time, and improve the filling quality and filling efficiency. Coal mine filling mining will play a more important role in the long-term planning of China’s green mine construction. Strengthening the scientific and technological research of the whole process of coal mine production based on active filling, the construction of universal filling technology and process system, the development of new solid filling materials, and the research of intelligent filling mining, will help the filling mining technologies in China’s coal mines have a very broad prospect.

The combination of water-jet and disc-cutter rock breaking is a key technology to improve the rock breaking efficiency of the full-face shaft boring machine and achieve the mechanized development of deep resources. It is a crux problem of selecting reasonable parameters for pre-cutting kerfs. In this paper, firstly, it examined the working characteristics of rock breaking with a disc-cutter driven by a conical cutter-head. Then, based on the cohesive element method, a discrete-continuous coupled numerical model for rock breaking with a disc-cutter under pre-cutting kerfs conditions was established. Comparing the intact rock mass, the influence of different pre-cut kerfs distances and depths on the stress and rock fragmentation characteristics of the rock breaking was analyzed. The three stage characteristics of dense core formation, blocky rock slag formation, and Hertz crack propagation during rock cutting with a disc-cutter were elaborated. The asymmetric fragmentation characteristics of the rock mass and the formation mechanism of rock slag in different regions were presented. Finally, a comprehensive analysis was conducted from four aspects: the force acting on the disc cutter, the rock breaking area, the specific energy consumption for rock breaking, and the degree of rock slag crushing, and the optimal range of distance and depth values for pre-cutting kerfs was determined. The research results indicate that the pre-cutting kerfs can significantly reduce the penetration force and lateral force during the rock breaking process of the SBM cutters. Compared with intact rock masses, the peak penetration force decreased by 44.0%−10.3%. The peak lateral force decreased by 35.2%−6.5%. When the spacing and depth of pre-cut kerfs are small, it will limit the range of rock breaking by the disc-cutter, and at the same time make the fragmentation of the rock mass smaller, resulting in an increase in specific energy consumption for rock breaking. As the pre-cut depth increases, the rock breaking volume first increases and then tends to be stabilized, while the specific energy consumption first decreases and then remains unchanged. Finally, it was determined that the cutting distance was 70−90 mm, and the best rock breaking effect was achieved when the cutting distance was 60−80 mm. The rock breaking volume was doubled compared to the case without cutting, and the specific energy consumption for rock breaking decreased by 69.2%. This provides a reference for the parameter design and determination of the cutter head.

Aiming at the development problems of deep coal reservoirs, such as deep burial, low permeability and complex stress field, this paper clarifies that the resource enrichment conditions, effective fracturing volume, effective horizontal section length, and good reservoir conditions are the key factors for high productivity on the basis of summarizing the exploration and development practice of the Daning-Jixian Block in the past five years. Under the guidance of the theory of “artificial gas reservoir” development, a technical system for the efficient development of deep coalbed methane was preliminarily established as follows. ① According to the reservoir resource conditions, structural preservation conditions and engineering fracturing conditions, a total of 11 indicators in three categories established the geological-engineering “dessert” evaluation standards of deep coalbed methane. ② Based on the techniques such as microstructural characterization, multi-scale fracture prediction, and 3D geological model construction, the quantitative and visual characterization of all elements of “geology + engineering” of deep coal seam was achieved. ③ Based on the guiding idea of “geological small scale, three-dimensional seismic microscale, drill along the target, less adjustment and fast drilling”, a three-stage geological-engineering geo-steering technology with an excellent design of pre-drilling trajectory, precise target entry and post-target fine-tuning as the core was developed.④ The optimization design of the five-in-one well network based on “in-situ stress field, natural fracture field, artificial fracture field, well type and orientation, well network and well spacing” realized the maximization of resource utilization and the maximization of gas field recovery. ⑤ According to the occurrence characteristics, seepage mechanism and production characteristics of deep coalbed methane, a reasonable production capacity evaluation and EUR prediction technology based on the rate-transient analysis method, the empirical production decline method, the numerical simulation method, and the empirical analogy method was formed. ⑥ Following to the design principle of “four-in-one” precision fracturing section and “fracture staggering + differentiation between fracturing segments”, a large-scale volumetric fracturing technology aimed at constructing artificial gas reservoirs was proposed.⑦ According to the characteristics of gas-water variation in gas wells, the optimal control technology of drainage and production in different production stages through the whole life cycle of wells was put forwarded. ⑧ Combined with the current progress of AI technology, and the characteristics of deep coalbed methane development law, gathering and transportation, the technology of gathering, transportation and digital intelligence integrating geological, engineering, and ground aspects was explored. Under the guidance of this achievement, 29 horizontal wells that have been put into production，with an initial production of 5×104−16×104 m3/d, an average of 10.2×104 m3/d, and the daily gas production of the block has exceeded 3 million cubic meters, which has important guiding significance for accelerating the large-scale production of deep coalbed methane in the eastern margin of the Ordos basin. Also the study establishes a reference and standard for the efficient development of similar resources.

The Xinjiang Uygur Autonomous Region has presented the expected resource conditions and work foundations for a large-scale coalbed methane (CBM) exploration and development, which shows that its CBM resources below the depth of 2000 m are 7.5 trillion m3, 450 CBM wells have been constructed, and the annual gas production has approached to 80 million m3. Xinjiang has put forward the goal of the annual CBM production of 2.5 billion m3 in 2025. Therefore, the large-scale and efficient development of CBM in Xinjiang has become an urgent and significant demand. In this paper, the main research progresses of Xinjiang CBM made in five key technical fields have been systematically summarized, including the CBM enrichment model and area optimization technology, the prediction and detection technology for sweet spot distribution, the technological strategy of the accelerated rolling development and rapid increase of reserves and productions, the geological adaptation technology system, and the cooperative exploration and development of CBM with coal, oil and gas. Then, the potential breakthrough directions have been analyzed and proposed. Research has shown that the coal reservoirs in Xinjiang show the unique geological characteristics of CBM, including widely developed multi-thick coal seams, low rank coal development, the frequent occurrence of steep coal seams, the significant deformation and structural control of coal bodies, complex hydrologic and outcrop conditions, and the gas-bearing and physical properties with three “low” (low gas content, methane concentration, and gas saturation) and five “high” (high gas intensity, porosity, stress change, reservoir pressure change, and permeability change). The Xinjiang CBM has multiple genetic types and enrichment models, including biogenic mechanism, thermogenic mechanism, and biogenic-thermogenic composite genetic mechanism, etc., and their corresponding enrichment models. Biogenic gas reservoirs or biogenic gas contribute widely. The distribution and occurrence patterns of CBM in Xinjiang show some significant differences between foreland basin and intermountain basin. Therefore, the first breakthrough direction is to innovate and form the scientific evaluation based on the principle of “two separation” (low-rank and middle- and high-rank; shallow and deep coal) and “two combination” (geological and engineering evaluation; multivariate data) and the precise target optimization technology based on “machine learning + three-dimensional geological modeling”. The sweet spot of deep CBM/CMG (coal measure gas) in Xinjiang is mainly the uplift of the depression in the basin, the depression of the uplift in the basin, and the slope around the basin margin. The potential well location is the structurally high position, and the potential reservoir is the fissure-developed primary structure coal seam or pore and fissure-developed coal bearing sand conglomerate reservoir. Then, the second breakthrough direction is the sweet spot prediction and exploration technology for deep CBM/CMG based on “new method of geophysics, rock physics and rock mechanics stratigraphy” and “new concept of geological and engineering sweet spot”. The basic principles of the accelerated rolling development are low-risk, short-cycle, high-efficiency, and multi-batch project deployment. The technical strategies of the rapid increase of CBM reserves and productions in the middle and shallow coal seams include the new well layout and construction in the new optimized block and the old well reconstruction for the increase of CBM production in the mature block. While this strategy for the deep coal seam is to give priority to deployment and development in the sweet spot in the deep but gentle slope in the large basin and the uplift in the basin. Then, the third breakthrough direction is the engineering deployment methods and technical strategies for the scientific accelerated rolling development, and efficient and rapid increase of the gas reserves and productions. The important progresses have been made in the engineering technologies of Xinjiang CBM, such as the differential optimization and deployment of the well type and pattern, the drilling and cementing with a low reservoir damage, the high reliability logging and well testing, the efficient staged fracturing with the multi-well types, and the drainage control with the low casing pressure and controlled pressure. The fourth breakthrough direction is to develop and construct a geological adaptability technology system for a large-scale and efficient exploration and development of CBM in Xinjiang. For the middle and shallow CBM and coal cooperative exploration and development, the gas extraction followed by coal mining, the co-extraction of CBM and coal, and the co-extraction of CBM and in-situ oil-rich coal should be conducted. For the deep CBM, oil, and gas cooperative exploration and development, the development of coal measure superimposed gas reservoir, the co-exploration and co-extraction of CBM and CMG, and the exploration and development of the whole petroleum system in coal-bearing sequence should be conducted. These cooperative exploration and development of deep CBM, oil, and gas is the fifth breakthrough direction, whose developments have been considered and explored. The results of this study are expected to provide the technical support and engineering decision reference for a large-scale and efficient exploration and development of CBM in Xinjiang.

During the coal mining process, the change in the floor stress state of coal seam will produce deformation and failure. The seam floor failure in different coal mining processes has a certain law. At present, the water disaster monitoring of coal seam floors based on the DC resistivity method mainly focuses on the resistivity response characteristics of floor deformation and damage. To investigate the temporal changes in the electrical properties of the coal seam floor during mining, this study employs the inter-hole DC perspective observation system and the time-lapse resistivity reflection coefficient method. Through numerical simulation and field tests, the study uncovers the temporal variation law of the resistivity of coal seam floor induced by mining activities. First, this paper compares the results of individual inversion and time-lapse resistivity change rates for a typical geoelectric model to validate the reliability of the inter-hole DC perspective time-lapse method. Next, considering the mining-induced damage to the coal seam floor, this paper analyzes the electrical response patterns and charac-teristics of the rise of confined water and the damage zone in the floor during the mining process. It also discusses the feasibility of using a time-lapse resistivity reflection coefficient to assess the depth of coal seam floor damage, offering a theoretical basis for field construction. Finally, , the on-site monitoring tests reveal the electrical change characteristics of coal seam floor during the coal mining process. The time-lapse resistivity reflection coefficient R is utilized to determine the damage depth of the rock layer of the working face floor, which is found to be 15 m. The study results demonstrate that the time-lapse characteristics of the resistivity of coal seam floor mining damage obtained by the inter-hole DC perspective method can mitigate the influence of formation factors and random noise in the monitoring data to a certain extent. Additionally, the time-lapse resistivity reflection coefficient can be utilized to determine the depth of coal seam floor failure. This method transforms the detection target from the single study of geological anomalies to the full life cycle dynamic monitoring of the floor damage of the working face in the process of coal mining and then realizes the detailed depiction of structural damage to the working surface floor.

The borehole transient electromagnetic method is used to detect the long-range water-bearing bodies around the borehole wall by using the advanced water exploration borehole in the heading roadway, which avoids the “one’s opinion in one hole” because the normal logging methods can only detect the rock layer of the borehole wall. At present, because of the whole space effect, the current borehole transient electromagnetic method cannot distinguish the orientation of abnormal bodies by the received single-component response, and it can approximate the orientation of abnormal bodies by multi-component response, but it is difficult to precisely locate and interpret the profiles by the visual and effective means such as imaging. Based on the theory of borehole transient electromagnetic method and azimuthal electromagnetic logging, this paper proposes a borehole transient electromagnetic positioning method with azimuthal coil scanning detection. The azimuth coil is used as the detection device to reduce the mutual inductance of the coil and enhance the detection effect of the borehole transient electromagnetic method. At the same time, by changing the rotation angle of the coil, the borehole wall is scanned by 360° to form a radial all-round detection of the borehole, aiming at a precise localization and profile interpretation of low-resistance abnormal bodies in the rock mass at the periphery of the borehole wall. Firstly, the authors derive an analytical expression for the mutual inductance of an azimuth coil, discuss the effect of azimuth angle on azimuth coil mutual inductance, and determine the optimum azimuth angle by numerical calculation. Secondly, a full-space 3D geological-geophysical model of the borehole with homogeneous medium and low-resistance abnormal bodies are established respectively and the numerical simulation of transient electromagnetic field is carried out. The multi-component response characteristics of the azimuthal coil scanning detection transient electromagnetic response are analyzed, and the law of transient electromagnetic response of azimuthal coil scanning detection is summarized, and the borehole transient electromagnetic positioning method with azimuthal coil scanning detection is determined. Namely, through the transient electromagnetic response characteristics of the axial and radial directions of the borehole, the position of the low-resistance abnormal bodies in the rock body at the periphery of the borehole wall is determined. Finally, by establishing the geological-geophysical model with two low-resistance bodies and using azimuth coils set to the best azimuth angle for numerical experiments, it is verified that the method can intuitively and effectively determine the orientation of low resistance abnormal bodies. The study shows that the azimuth coil scanning detection results of the borehole transient electromagnetic method can better reflect the transient electromagnetic field anomaly caused by the low-resistance abnormal bodies in the rock body at the periphery of the borehole wall, and the resolution of the full-space apparent resistivity imaging results is high. Based on the transient electromagnetic response characteristics of the axial and radial directions of the borehole, the borehole transient electromagnetic positioning method with azimuthal coil scanning detection has a high resolution and localization accuracy for the low-resistance abnormal bodies in the rock body at the periphery of the borehole wall. The research results provide a theoretical basis for the practical application of the borehole transient electromagnetic positioning method with azimuthal coil scanning detection.

The safety in the coal-producing mines in China is continuously improving, but coal and gas outburst accidents still occur. The prediction of coal and gas outbursts allows the scientific application of outburst prevention measures, which can ensure the safe coal mining to a certain extent. Machine learning is an interdisciplinary field involving probability theory, statistics, and computer science, which can explore the nonlinear relationship between outburst accidents and its associated indicators. The application of machine learning in coal and gas outburst prediction has received relatively widespread attention, and with the rapid progress of artificial intelligence and computer technology, it will play a greater role in the field of outburst prediction. Therefore, this paper provides a comprehensive review of the research on machine learning in coal and gas outburst prediction, analyzes the difficulties in outburst prediction and prospects its development direction. Firstly, the paper provides a brief overview of the research status on the hypothesis, occurrence mechanism, and prediction index selection of coal and gas outbursts. Then, it summarizes the research progress in the field of outburst prediction, including the application of support vector machines, neural networks, extreme learning machines, and ensemble learning algorithms. In addition, it also points out the existing problems in the current research, such as imbalanced samples, missing data indicators, and small sample sizes. Finally, the paper gives an outlook on the developments of coal and gas outburst prediction based on machine learning, including improving algorithm performance, optimizing feature engineering, and increasing sample size. With the continuous improvement of computer performance, more powerful models may be proposed, which can further improve the prediction accuracy of outburst accidents.

Aiming at the real problems such as the occurrence of coal and gas outburst and based on the hypothesis of comprehensive action of coal and gas outburst, a method of gas hydration and solidification to prevent coal and gas outburst is proposed. The core of this method is to solidify the gas in coal seam to form gas hydrate, which can not only reduce the gas pressure, but also improve the coal strength, so as to reduce or eliminate the risk of coal and gas outburst. Based on the idea of “coal and gas outburst prevention using hydrate”, the test of gas hydrate formation in coal and the in-situ test of the mechanical property-permeability of gas hydrate bearing coal have been performed, with the numerical modeling technique of the triaxial compression of the gas hydrate bearing coal proposed. The techniques are implemented by comprehensively applying the methods of theoretical analysis, development of testing equipment, indoor test and numerical analysis. In terms of coal and gas outburst prevention, the thermodynamic and kinetic conditions of gas hydrate formation are its theoretical basis, the stable storage of gas hydrate is its technical precondition, and the reduction of gas pressure and the improvement of mechanical properties are its key measures. This paper focuses on the cross mechanics related to the gas hydrate bearing coal. The results show that: ① the theoretical framework of gas solidification technology by the hydrate method for outburst prevention has been initially formed, and the meso-mechanism of improving the mechanical characteristics of coal before and after gas hydration has been preliminarily explored by means of the numerical simulation. ② At present, it has been confirmed that the hydrate formation in coal can not only reduce the gas pressure, but also improve its mechanical properties. High saturation can obviously improve the peak strength of coal. ③ Gas hydrate formation experiences three stages: rapid, slow and stable stage. Additionally, the formation of hydrate will cause the gas seepage channel in the coal to be blocked, resulting in a decrease in its permeability. ④ High gas pressure and high CH4 concentration not only help to increase the saturation but also delay hydrate decomposition, which is conducive to the stable existence of the hydrate. However, a large number of repetitive experiments are still needed to verify the reliability of the method to build up a generalized database. By analyzing current research findings, the limitations and challenges that still exist are discussed, with further research interests pointed out.

The permeability coefficient of coal seams is a key parameter that judges the difficulty of gas flow in coal seams. In the current calculation formula for the permeability coefficient of coal seams, the coefficient of the nonlinear partial differential equation with variable pressure is assumed to be a constant, which leads to significant errors in the theoretical derivation results and results in significant deviations in the permeability coefficient measured on site. To solve the inaccurate determination problem of the coal seam permeability coefficient, this paper derived the process of using the radial flow rate method to test the coal seam permeability coefficient, and pointed out the problems of this method during the derivation process. Based on the Langmuir's gas content and Darcy's law, a dimensionless model was established, and the model solution results were inverted and fitted. A new calculation formula for the coal seam permeability coefficient was obtained, which was verified by on-site drilling data. The current testing method for coal seam permeability coefficient was revised, and an accurate and reliable new method for calculating the coal seam permeability coefficient was proposed. The results indicate that using a parabolic equation to represent the coal seam gas content and treating variable p1.5 as a constant to derive the coal seam permeability coefficient calculation formula is equivalent to fitting the gas content into a proportional relationship with the square of pressure. There are theoretical problems and significant errors in actual calculations. Using the Langmuir dimensionless model to calculate Y' for inversion fitting can solve the shortcomings of current calculation methods. When the product of the adsorption constant b and the original gas pressure p0 (the dimensionless original gas pressure) is different, the function curve of the dimensionless gas emission velocity Y' and the dimensionless time Fo' is significantly different. Therefore, the permeability coefficient calculation formula containing the dimensionless original gas pressure was obtained. When the coal seam and drilling conditions are constant, the values of the coal seam permeability coefficient λ calculated from the gas emission volume at different times have a good reproducibility. The new on-site measurement method for the permeability coefficient of coal seams is completely the same as the current method without adding additional workload. However, the new calculating method is more accurate and reliable.

In view of the uniqueness of the occurrence conditions of coal resources in Xinjiang and the fragility of the ecological environment in the coal occurrence area, it is urgent to develop coal resources in Xinjiang scientifically. Therefore, in this paper, the geological occurrence conditions, hydrogeological conditions, physical geography and ecological environment conditions of coal resources in Xinjiang were briefly discussed, and the exploitation potential of coal resources was analyzed. The results show that the coal resources in Xinjiang are extremely abundant, with an estimated coal resource of 2.19 trillion tonnes in the entire region, accounting for more than 40% of the total estimated coal resources in China. There are 24 coal fields in Xinjiang with estimated resource levels exceeding 10 billion tonnes, of which 5 have estimated resource levels exceeding 100 billion tonnes, 8 have estimated resource levels between 40 billion−100 billion tonnes, and 11 have estimated resource levels between 10 billion−40 billion tonnes. Among the potential coal resources, shallow resources below 1000 meters account for 52.8%. The main coal rank of Xinjiang’s coal resources is low-rank bituminous coal and medium-rank bituminous coal, fol-lowed by high-rank bituminous coal in middling coal rank coal, while lignite in low-rank coal, ultra-high rank bituminous coal in middling coal rank coal and anthracite in high-rank coal have extremely limited distribution range and quantity, accounting for a very low proportion of the total resources. Taking into account the transportation of coal from Xinjiang, the transmission of electricity from Xinjiang, the transmission of natural gas from the west to the east, and the local coal chemical industry plan, it is expected that Xinjiang’s coal production capacity will exceed 800 million tonnes by 2035. On this basis, an ecological environment carrying capacity evaluation index system was constructed, and the ecological environment carrying capacity of the five major coal mining areas planned and constructed in Xinjiang was evaluated. The results show that the overall ecological environment carrying capacity of the coal resource areas in Xinjiang is at a medium to low level, and the average ecological environment carrying capacity of the five major coal mining areas is ranked as Yili (0.42)>Kubai (0.38)>Hefeng (0.31)>Zhundong (0.25)>Tuha (0.22). It shows a decreasing trend from west to east. In response to the conditions and potential of coal resource development in Xinjiang, strategies have been proposed to optimize the layout of coal resource development, promote mining technology upgrading, promote intelligent mining technology, strengthen the concept of green mining, and expand diversified channels for coal utilization.

The fragile ecological environment in the western coal mining areas of China, compounded by intensive mining activities, has led to water and soil erosion, soil degradation, and damaged root systems. With a low plant water use efficiency, the ecological restoration becomes challenging, making the improvement of water use efficiency a key aspect in the ecological restoration or reconstruction of western mining areas. Soil water is a critical factor limiting the ecological restoration of arid and semi-arid coal mining areas, as it connects atmospheric water, surface water, groundwater, and vegetation growth, serving as an important carrier for water circulation and nutrient transport. Efficient and rational utilization of soil water is crucial to the success of ecological restoration. Therefore, investigating plant root water utilization strategies plays a significant role in the ecological restoration of western coal mining areas. This paper analyzes the main research methods of plant water use at home and abroad, compares the advantages and disadvantages of different methods, and reviews the corresponding research progress. In the damaged ecological environments of arid and semi-arid coal mining areas, the application of plant-microbe combined microbial remediation technology can improve plant water use efficiency and enhance plant water use strategies. At the same time, the microbial inoculation reduces the proportion of water absorption by plants from shallow soil layers, effectively increasing the absorption and utilization of water from deep soil layers by plants, thereby enhancing plant water use efficiency. This enables the inoculated plants to exhibit a higher ecological adaptability in the arid and semi-arid coal mining areas. This paper analyzes the current research progress and existing problems of plant water use in the western coal mining areas, discusses the improvement of water use strategies through microbial remediation in mining areas, and proposes the impact of different plant combinations on water use strategies and their research focuses in the ecological restoration of western arid coal mining areas. This lays a solid foundation for achieving green, sustainable, and high-quality development in the arid and semi-arid coal mining areas, and has important ecological application value.

In view of the natural endowment of mercury in fossil fuels and mineral resources, as well as the mercury emission controlling and regulating in the energy and resource utilization processes, the research and development on the mercury continuous emissions monitoring system (Hg-CEMS) with proprietary intellectual property rights is the most important requirement in science and technology in China. As a critical component of the Hg-CEMS system, the flue gas pretreatment system is a core technology that limits the development and application of the Hg-CEMS technology in China. This paper presents a comprehensive review of the research progress in the four key modules of the Hg-CEMS flue gas pretreatment technology, including the dilution sampling, Hg0/Hg2+ separation, Hg2+ reduction and Hg2+ calibration gas generation. Firstly, the dilution sampling techniques are highlighted in their characteristics and principles. The working principles, structures, and design considerations of the critical parameters for both critical hole and thermal dilution injectors are summarized. Emphasis is focused on the connection of numerical simulation with the optimal design methodology for the thermal dilution injector and critical hole. Secondly, regarding the Hg0/Hg2+ separation technology, various partitioning methodologies encompassing the wet absorption separation, physical adsorption separation and chemical adsorption separation are discussed. Particular attention is given to the separation and adsorption efficiency of the advanced dry chemical adsorption techniques involving the novel selective adsorbents of KCl and CaO with their updated theoretical and experimental outcomes under practical operating conditions. Thirdly, in aspect of the Hg2+ reduction technology, a comparative analysis of wet chemical reduction, low-temperature reduction and high-temperature reduction techniques is expatiated. Particular focus is on the active components of solid-state reducing agents, the impact of temperature on the reduction of divalent mercury, and the detrimental influences of flue gas components on the re-oxidation of the reduced elemental mercury in the low-temperature reduction techniques. An in-depth investigation of the impact of filler materials, acidic gas components and acid removal techniques on the reduction of divalent mercury in the high-temperature reduction techniques is highlighted. Finally, facing the technical problems, a solid generation method of the Hg2+ calibration gas is invented and its industrial utilization feasibility is verified in chemistry and experiments. In conjunction with the current status of research and application of the Hg-CEMS technology, the research technical routs, the solutions to some problems and development prospect for the above-mentioned four key modules are put forward.

China’s total carbon emissions are approximately 11 billion tons, with around 40% of CO2 being produced by the coal-fired power plants (CFPP). Therefore, reducing carbon emissions from the CFPP is critical in achieving the Dual-Carbon target. This paper focused on the advancements in the low-carbon/carbon-neutral fuel substitution technologies (such as biomass, sludge, hydrogen/ammonia, etc.) and the CCUS (carbon capture, utilization and storage). The CFPP coupled with biomass includes direct and indirect coupling, but are subject to the supply and price of biomass feedstock. To address these challenges, a comprehensive “planting-harvesting-transportation-storage-pretreatment-combustion” approach was recommended to ensure an effective control throughout the entire chain. Initial pilot test on a 660 MW CFPP revealed a substantial reduction in CO2 emissions by 772500 tons annually. The high-water content of municipal sludge, reaching up to 80%, necessitates drying prior to entering the boiler. Current steam drying and flue gas drying technologies entail substantial investment and operational costs, with the dried sludge still retaining high water content and associated problems such as odor. Consequently, the blending ratio in the CFPP remains below 8%. A sludge carbonization technology based on a biomass heat source can address these challenges, which allows for the direct production of odorless sludge char in sewage plants with a calorific value of about 10.26 MJ/kg. This technology enables an increased blending ratio in the CFPP to 20%−30%, thereby significantly reducing coal consumption and CO2 emissions. The blending of hydrogen/ammonia necessitates addressing the issues of ammonia escape and NOx emission under high blending ratios. Experiments for co-firing of coal and ammonia were conducted on 300 MW and 600 MW CFPP in China to address the challenges of ammonia escape and NOx emissions under high blending ratios. The results showed that combustion control can achieve a higher NH3 burn-up rate with a slight increase in NOx emissions. However, the commercialization of hydrogen/ammonia blending in the CFPP is constrained by the cost of hydrogen and ammonia. The commercialization of pre-combustion decarbonization technology, such as IGCC, faces significant limitations due to high costs. Several foreign demonstration projects were discontinued. The construction costs and equipment reliability are crucial for promoting the commercialization of this technology. Carbon capture technologies in combustion processes include oxygen-enriched combustion and chemical chain combustion. The power generation efficiency of atmospheric oxyfuel combustion is lower by 8%−12% compared to air combustion due to the energy consumption associated with air separation and recycling processes. Transitioning from atmospheric oxyfuel combustion to pressurized oxyfuel combustion can further increase the net power generation efficiency. Notably, China has constructed the world’s largest 4 MW chemical-looping combustion (LCL) demonstration plant. The LCL also has a potential application in the gasification industry. Post-combustion carbon capture predominantly employs the solution absorption technology, while the solid adsorption technology offers a lower regeneration energy consumption. However, some challenges remain in reducing energy consumption and costs to facilitate the large-scale commercialization of this technology.

Coal gasification fine slag (CGFS) has high utilization value, but the low recovery rate of residue carbon greatly restricts its resource utilization. The oil agglomeration separation method has obvious advantages in the CGFS separation process, but its separation efficiency is severely limited by the symbiotic structure of carbon and ash. In order to break through the bottleneck problem of residue carbon separation and enrichment technology by oil agglomeration method, the effects of ultrasonic time, ultrasonic power, fluid shear time and their interaction on oil agglomeration and separation were investigated in this paper. Combined with BET, particle size distribution, FT-IR, XPS and SEM-EDS analysis methods, the strengthening mechanism of ultrasonic cavitation and fluid shear (UC-FS) pretreatment on oil agglomeration separation was revealed. The results show that when the ultrasonic power is 270 W, the ultrasonic treatment time is 29 min, and the fluid shear time is 23 min, the concentrate with ash content of 9.55% and the tailings with ash content of 91.51% can be obtained, and the combustible recovery rate can be increased to 90.54%. Ultrasonic cavitation gradually loosens the original dense carbon ash structure, and promotes the development of the pore structure of CGFS in coordination with the scouring effect of fluid shear, which increases the dissociation degree of carbon ash particles and thus reduces the ash content of concentrate. UC-FS pretreatment can effectively increase the proportion of hydrophobic groups such as C—C, C=C and C—H on the surface of carbon residue, increase its contact angle from 110.34° to 121.16°, and further expand the difference of hydrophilic and hydrophobic properties on the surface of carbon and ash particles, thus improving the effect of oil agglomeration separation. The mechanism of UC-FS synergistic pretreatment to improve the efficient separation of carbon ash particles is mainly attributed to the micro-abrasive effect generated by the coupling of ultrasonic cavitation bubbles and fine-grained microspheres. This study can provide theoretical basis and technical guidance for the separation and utilization of CGFS.

Under the carbon peaking and carbon neutrality strategy, biomass has attracted much attention due to its characteristics of regeneration, low pollution and zero carbon emissions. The imperfects of biomass, such as the loose structure and low energy density, can be effectively solved by briquetting, and the resulted fuel pellets can be used as a substitute for fossil fuels, which is of great significance for the construction of new energy system. In the paper, the influencing factors of the hot briquetting process of biomass were summarized, and the evolution behavior and binding mechanism of biomass particles during the hot briquetting process were analyzed and discussed. Biomass briquetting process mainly includes cold briquetting and hot briquetting. Compared with cold briquetting process of biomass, hot briquetting with lower energy consumption can produce the biomass fuel pellets with higher quality. The moisture content (4%−15%) of the raw biomass has greater influence, the briquetting temperature (70−150 ℃) has relatively smaller effect on the density of the fuel pellets, and the briquetting pressure (60−130 MPa) and the particle size ( < 2.5 mm) of the raw material show the different impact on the density of the fuel pellets from different biomass. During the hot process, cellulose mainly plays the role of supporting skeleton, hemicellulose and lignin play the role of binder. In the microcosmic process of hot briquetting process, the inertia movement and subsequent viscoelastic-plastic deformation of the biomass particles occur and the mechanical interlock is formed between the particles. The brittle particles are broken and the natural viscous components are released, and thus, the bridge linkage between the particles is formed under the integrated effects of moisture, temperature and pressure. Mechanical interlocking and bridging reduce the distance between biomass molecules and promote the generation of intermolecular forces. Based on the above-mentioned mechanism of the hot briquetting of biomass, the quality of the resulted fuel pellets can be improved by biomass component adjustment, biomass blending or hydrothermal pretreatment. In the future, the molecular dynamics simulation method will be used to investigate the biomass briquetting process to obtain the molecular bonding mechanism of biomass components, which is conducive to further exploring the hot briquetting mechanism of biomass, and provide important guiding significance for the preparation of fuel pellets and molding materials from biomass.

Coal-fired power generation is an important guarantee for the energy security in China, but a large amount of CO2 is emitted from flue gas. At the same time, a large amount of fly ash is also generated. The CO2 mineralization by fly ash and its product utilization are able to achieve the goals of solid waste treatment and long-term CO2 storage. At present, there are still some shortcomings in the CO2 mineralization technology by fly ash, such as low mineralization efficiency, long reaction time, and small processing capacity. The corresponding key scientific issues and technical bottlenecks need to be addressed urgently. In this paper, the basic principle of CO2 mineralization by fly ash is briefly introduced. The influencing mechanisms of different reaction conditions on alkali metal ion leaching and CO2 mineralization are analyzed. The advantages and disadvantages of three processes, namely the CO2 direct mineralization reaction process, the alkali metal pre-leaching process, and the CO2 pre-absorption process, are compared. The key technology of CO2 mineralization by fly ash is proposed, including the efficient alkali metal ion leaching, the enhanced CO2 mineralization reaction process, the intelligent equipment for fly ash mineralization CO2, and the comprehensive evaluation of mineralization effect. The physical and chemical properties of its mineralization products are clarified. And the utilization of its mineralization products is explored. Finally, three key scientific issues are summarized, including the rapid leaching of alkali metal ions from fly ash and the efficient mineralization of CO2, the multiphase mixing and reaction laws in large CO2 mineralization reactors, and the control mechanism of the mineralization product properties. The research direction of the entire chain including basic research, key technology and equipment development, and engineering application is proposed, providing a reference for the efficient mineralization of flue gas CO2 by fly ash and the utilization of its products, which is of great significance for achieving the carbon neutrality goal and utilization of solid waste.

Coal mining machine is the core equipment of completely automated working face, and the research and development of intelligent coal mining robot is crucial for achieving the intellectualization of fully mechanized working face. This paper comprehensively analyzes the current research status of sensing detection, position and attitude control, speed control, cutting trajectory planning, and tracking control in the coal mining machine roboticization process, and proposes five key technologies that must be solved in the development of intelligent shearer robots, including sensing and detection, pose control, velocity control, cutting trajectory planning and tracking control. Aiming at the problem of intelligent perception, this paper proposes the construction thought of a coal mining robot intelligent perception system, as well as the architecture of a coal mining robot intelligent per-ception system. The architecture of the intelligent perception system for coal mining robots is outlined, enabling a comprehensive sensing of running state, posture, environment, and so on, thereby ensuring the safe and reliable operation of intelligent coal mining robots. In terms of the position and attitude control problem of intelligent coal mining robots, the intelligent PID position and attitude control thought is proposed, along with an improved genetic algorithm-based PID pose control method, enabling precise pose control for the coal mining robot. As to the problem of velocity control, the thought of cutting load measurement based on the fusion of “force-electricity” heterogeneous data is proposed. Additionally, a neural network-based algorithm for cutting load measurement is presented, achieving an accurate load measurement. Furthermore, a traction and cutting speed adaptive control approach is proposed, including an artificial intelligence-based decision-making method for traction and cutting speed and a sliding mode control method for traction and cutting speed with disturbance rejection. This approach enables a precise and adaptive speed control for the coal mining robot. Regarding the problem of cutting trajectory planning and tracking control, the precise cutting trajectory planning thought is proposed, incorporating geological data and historical cutting data into a cutting trajectory planning model. The precise cutting trajectory tracking control thought is proposed, and an intelligent interpolation algorithm-based cutting trajectory tracking control method is given, achieving a high-precision trajectory planning and accurate tracking control for the coal mining robot. Considering the “position-attitude-velocity” collaborative control problem, the intelligent optimization idea of "position-attitude-velocity" collaborative control parameters is proposed, which utilizes an improved particle swarm optimization method based on multi-system constraints to optimize the coordinated control parameters, resulting in intelligent and efficient operation of the coal mining robot. The in-depth investigation of these five key technologies for intelligent coal mining robot provides some valuable insights for accelerating the development of high-performance, efficient, and reliable intelligent coal mining robot.

In view of the intelligentization of coal mine roadway excavation, this paper discusses the current development status of four major categories of intelligent fast excavation equipment, including continuous mining machine, excavation and anchor machine, full-section excavation system, and anchor excavation machine, analyzes the applicability of the four major categories of intelligent fast excavation equipment with the geological conditions, proposes some key technological issues for the realization of intelligent coal mine excavation which need to be resolved, and also explores the information transmission and intelligent analysis technology, intelligent perception technology, precise positioning and navigation technology, autonomous stereotyped directional cutting technology, remote and autonomous cutting control technology of road-header and multi-level and multi-process intelligent cooperative control technology, as they are the basis for the realization of intelligent roadway excavation. Based on the key technological issues needed to be solved in the mine roadway excavation under the complex geological conditions, the paper puts forward the design method of systematic analysis, modular design and optimal combination of functions, according to the functional requirements of the excavation operation and the requirements of the excavation process. A multi-level digital twin architecture of virtual control and virtual-reality combination is studied based on the multi-dimensional information reproduction of heading equipment, environment, and geological structure to realize the remote control of road-heading machine. A control method that integrates single-machine intelligence, system synergism, and synergism of underground intelligent control and surface remote monitoring is proposed. A new type of flexible advance support technology without repetitive crushing, multi-stage telescopic cutting technology of cutting section, and multi-rig parallel operation technology of intelligent anchoring unit have been developed, and a new type of combined unit for rapid roadway heading operation with a parallel operation of excavating, supporting, anchoring, transporting, and exploring processes has been also developed, and a flexible parallel operation technology of excavation robot, advance support robot, anchoring robot, and auxiliary transportation robot group has been proposed. A data-driven multi-machine, multi-process collaborative control behavior planning and decision-making method is proposed. In addition, it is proposed to construct a complete coal mine underground cross-system full-temporal-spatial information digital sensing system, build a data sensing intelligent monitoring platform with multi-parameter, multi-scale and full-temporal-spatial characteristics, that integrates the production state of underground site, spatial information of roadway, state of heading equipment, and risk information, etc., and realize a real-time communication between virtual system and actual tunneling system, so as to realize the intelligent and less-manned heading through data-driven planning and analysis.

The sheave is an important part of a mine hoisting system. Once it fails, it will not only affect the production efficiency of coal mine, but also cause some safety risks. Poor lubrication is one of the main causes of sheave failure. In view of the low efficiency and difficulty in ensuring the uniformity and timeliness of lubrication caused by the current manual lubrication method commonly used in coal mines, this paper presented a new intelligent lubrication system for sheave bearings and implemented it on-site application. First of all, starting from sheave structure and considering the different operating modes of the sheave shaft end rolling bearing and the traveling wheel sliding bearing, it was proposed to use a combination of automatic lubrication and manual assistance to lubricate the sheave bearing. Through a real-time monitoring of the lubrication system, it realized the intelligent distribution function of single pump and multiple points with different grease amounts, and also provided the waste grease recovery function to avoid damage to bearings by waste oil. Then, an intelligent control strategy based on the identification of abnormal lubrication status was studied, and the lubrication cycle and lubrication amount of the system were adjusted based on the judgment results of the lubrication status. Subsequently, considering the impact of lubrication status identification accuracy on system operation results, an intelligent identification model of lubrication status based on the combination of Locality Preserving Projections (LPP) and Support Vector Data Description (SVDD) was constructed. In view of the problem that the number of neighboring points in the feature dimensionality reduction method will seriously affect the dimensionality reduction effect, it was proposed to use the information entropy difference between the high and low dimensional feature sets of the sample set as the objective function, and apply the particle swarm optimization algorithm to optimize the parameters of the LPP algorithm. The model was verified using on-site measured data. The results show that the proposed method can effectively identify the abnormal state of the sheave bearing, and the identification accuracy can reach 82% under on-site working conditions. Finally, an on-site application study of the intelligent lubrication system for pulley bearings was conducted in a coal mine. A single pump was used to lubricate four pulleys. The results show that the lubrication system can obtain its own operating parameters in real time and achieve remote control, ensure the continuation and uniformity of the lubrication effect, and meet the actual requirements of the mine site.

This is an article in the field of earth sciences. Jiulong area is the most concentrated area of Yanshanian granite found in western Sichuan, including Tiechanghe, Qiaopengzi-Landiao and Xinhuoshangranite. In this paper, LA-ICP-MS zircon U-Pb dating were carried out to determine the formation age of the granite， and its temporal-spatial relationship with the surrounding granites, providing a basis for the comparative study of Liwu copper deposit in the southern margin of Songpan-Ganzi block. The results show thatthe diagenetic age of Huajiaoping granite is (163.1±1.4) Ma, andit underwent magmatic or tectonic thermal events at (146±3) Ma, which is consistent withthe geological events ofTiechanghe, Xinhuoshan and Luomogranite. The magma temperature of Huajiaoping granite is 592～727 ℃ (average temperature 648 ℃), which is significantly lower than that of Qiaopengzi granite (766～804 ℃). Combined with the regional geological background, about 170 ～ 140 Ma, the lithosphere in the southern margin of Songpan Ganzi block is in the extension stage. The granite magma activity dominated in the early stage (163 Ma) by Huajiaoping granite, and in the late stage (146 Ma) by magmatism or tectonic thermal events. This discovery enriched the Yanshannian granitic magmatic thermal events in Jiulong area.

This is an article in the field of earth sciences. To reveal the mineral chemistry characteristics and metamorphic temperature of garnet in the Liwu Group due to core of Jianglang dome, the major, trace and rare earth elements of garnet were analyzed at different locations in this paper. The results show that the major-element composition of garnet in schist from the Jianglang dome is mainly Alm. ICP-MS (average content 85.82%) and LA-ICP-MS (average content 83.51%) is basically consistent within the error range of the Alm content obtained.The total content of rare earth elements (REE) is high, and show obvious LREE-depleted and HREE-enriched left-declined REE distribution patterns, with unobvious Eu anomalies and negative Ce anomalies, Enriched in large ionic strength elements (U, Ta, Hf)and depleted high field lithophile elements (K, Sr, Ba). In addition, the formation temperature of garnet in schist from the Jianglang dome is 512～583 ℃, and the formed metamorphic pressure is relatively low. It is a negative correlation between the metamorphic temperature and the distance to the Xinhuoshan granite. In conclusion, the Jianglang dome experienced “Barrovian-type” metamorphism of high greenschist facies.

This is an article in the field of earth sciences. Xidamingshan polymetallic ore concentration area is critical mineral prospecting district in Guangxi. With the promotion of the large-scale mineral breakthrough work, the Xidamingshan mineral exploration, the Nongtun large-scale Pb-Zn deposit has been newly discovered. However, the understanding of the metallogenic characteristics of the deposit, especially the genesis of the deposit, is still at the superficial stage. Based on detailed field geological investigations and previous work, this paper systematically summarizes the regional metallogenic geological background, mining area and geological characteristics, and analyzes the genesis of the Nongtun lead-zinc deposit to find out the metallogenic mechanism. The study shows the Nongtun Pb-Zn deposit is related-magmatic hydrothermal deposit, the ore-forming fluids originated from magmatic, and later mixed with meteoric water. The fluids extracted Pb and Zn ore-forming elements from the strata during long-distance transport, and combined with S of magmatic fluids to synthesize [HS]-ligand that converged in the fracture zone and transported to the shallow part, thus forming Pb-Zn ore vein. The above research results have established the metallogenic model of the Nongtun Pb-Zn deposit, which provides a good guidance for prospecting prediction and exploration.

This is an article in the field of earth sciences. Based on the 1∶25000 trench soil geochemical survey carried out in the Yongxi gold polymetallic mining area in Danba County, this paper reveals the element geochemical characteristics and anomaly distribution laws represented by gold, silver, arsenic and antimony in this area, finds a number of valuable geochemical comprehensive anomalies, analyzes the prospecting potential of geochemical anomaly areas, further narrows the prospecting scope, and delimits a prospecting target area. The engineering verification of the target area has achieved good prospecting results, which proves that the trench soil geochemical survey method is effective in the geological exploration work in this area, and provides a scientific basis for further geological work.

This is an article in the field of earth sciences. The newly discovered Maoping graphite deposit is a super-large crystalline graphite deposit that is located in the middle-northern section of the Kang-Dian fault-uplift belt on the western margin of the Upper Yangtze paleo-continent, and the research on the source of mineralization and its mineralization age is relatively weak. The orebodies occur in the epimetamorphic rocks of Mesoproterozoic Tianbaoshan Formation. In this paper, the geochemical characteristics of major ores, trace amounts and rare earth elements were mainly studied. The results show that the original rock of the ore-bearing rock layer is parametamorphic rock, a set of carbonaceous quartz-bearing siltstone, which is deposited in an oxygen-deficient environment. The characteristics of trace elements indicate that the original rock of the ore body is formed by the deposition of offshore terrigenous clasts. The ores show sedimentary characteristics of coastal tidal flat facies, with an average ΣREE of 158 g/t, average δ Ce value of 0.63 (weak negative anomaly), and an average δ Eu value of 0.69 (negative abnormaly). The graphite ore body has a δ13C value of -28.35‰～-29.08‰, with an average of -28.59‰, indicating that the mineralized carbon is dominated by organic carbon. The LA-MC-ICP-MS Zircon U-Pb of amphibole zircon from Xijie hornblende diorite Zircon is (823.4±3.6) Ma, which is later than the formation era of volcanic rocks of the Tianbaoshan Formation (954 Ma), representing the time of superposition metamorphism of graphite. In summary,the genetic type of the ore deposit is sedimentary- metamorphism and its metamorphism may include the regional dynamic metamorphism of Jinning period that is superimposed by contact metamorphism.

This is an article in the field of earth sciences. Magmatic rocks of the Gondwana Belt are one of the most popular problems in basic geological research on the Xizang-Qinghai Plateau. In this paper, we analyze the physical origin and regional tectonic properties of the Gachatai granite using LA-ICP-MS zircon U-Pb dating method, combined with the geochemical characteristics of the rocks and various graphical methods. The rocks are characterized by high alkali (average Na2O+K2O content of 6.26%), potassium (K2O/Na2O=1.03), low TiO2 (average 0.50%) and quasi-aluminous (aluminum saturation index A/CNK=0.933～1.033, average 0.991) high potassium-calcium-alkaline rock system. Rare earth elements show negative anomalies at Eu, which is the Eu-deficient type, and Ce has weak negative anomalies; trace elements show enrichment of large ion-parental elements Rb, Th, Nd, La and K; high field strength elements Nb, Ba, U, Ta, Ce, Sm and Ti are deficient; reflecting the mixed crust-mantle type of magma origin and the presence of subduction oceanic crustal melting. The zircon LA-ICP-MS U-Pb isotopic age is （345.3±1.8） Ma, and its formation age is Early Carboniferous. The analysis of the regional geological data suggests that this magmatic event is a product of the formation of the northern part of the eastern Gondwana continent after the breakup of the Rodinia supercontinent. The project points go to I-type granite, the discriminant diagrams indicate it’s formed from continental island arc, going through time before plate collision to co-collisional orogenic movement, which indicates a long period time of magmatic evolution; the rock geochemical characteristics show the environment of magmatic evolution changed from the start of island arc(primary island arc)-development(early stage island arc)-maturement(full-grown island arc).

This is an article in the field of mineral processing engineering. Some unavoidable ions commonly present in the slurry solution have an important influence on the flotation separation of lead-zinc sulfide ore. The unavoidable ions in the slurry mainly come from the water used in the processing plant, the dissolution of minerals, the dissociation of activators or depressants, and the primary ions introduced by the release of fluid inclusions and the secondary ions introduced during the grinding process. This article summarizes and analyzes the effects on the flotation separation of lead-zinc sulfide ore which is caused by the primary ions introduced in the slurry and the secondary inevitable ions introduced in the grinding system. It is found that both primary ions and secondary ions have obvious effects on the flotation behavior of lead-zinc sulfide ore. And many scholars have done a lot of research on this phenomenon. In this paper, a great breakthrough has been made through the adjustment and control of reagents and changes in the grinding environment. At the same time, this article provides important research ideas for follow-up researchers. The focus of this article is how to integrate the previous research results with the field process significantly, how to eliminate inevitable ions from the source without affecting the industrial economy, The important direction of future research is still how to reduce the influence of inevitable ions on the flotation index from the field process.

This is an article in the field of metallurgical engineering. A copper cobalt ore Congo is an oxide ore with Cu 3.43% and Co 0.42% respectively. In this paper, the five stage cycle leaching process of leaching solution was used for the copper and cobalt leaching. The optimum conditions were as follows: the amount of sulfuric acid was 7.4% of the ore mass, the amount of sodium sulfite was 1.68 times of the theoretical amount, the grinding particle size of -74 μm accounts for 75%, leaching temperature was 45 ℃, the single-stage leaching time was 4 hours, and the liquid-solid volume mass ratio was between 2/1 and 3/1, the results showed that the leaching rate of copper and cobalt were 96.85% and 95.67% respectively. According to this leaching process, the amount of sulfuric acid was reduced by 6 kg/t compared with the primary leaching, and the total solution amount in the leaching process was reduced by about 1/4, which made the amount of subsequent cobalt precipitation and copper extraction solution was reduced.

This is an article in the field of mineral processing engineering. Barium slag is toxic solid waste, and a large amount of barium slag is piled up to seriously harm the environment and cause huge waste of national land resources. Acid-dissolving barium in acid leaching barium residue is one of the best ways to dispose of barium residue and recover barium. The paper adopts the flotation process to recover the barium sulfate in the acid leaching tailings of the enriched barium slag, in order to realize the comprehensive recovery of barium resources in the barium slag. The experimental research of the flotation recovery of barium residue acid leaching residue shows that. Under the condition that the amount of sodium carbonate is 2000 g/t, the amount of sodium silicate is 500 g/t and the amount of sodium oleate is 3000 g/t, through the flotation closed-circuit process of one roughing, four beneficiation, and two sweeping. Obtained the flotation index of 85.38% barite concentrate grade and 69.35% recovery rate. Concentrate products meet the barite standards used in the industrial production of barium carbonate.

Due to high-intensity mining and complex geological conditions, frequent occurrence of rock burst disasters in deep coal mines in China is posing serious threats to mine safety and efficiency. The insufficient locating accuracy of the seismic monitoring system in burst-prone coal mines is still presented, which leads to difficulties in accurately identifying and controlling coal burst hazards. To precisely characterize spatial evolution of seismic activities and reduce the impact of location error on the seismic pre-warning, this paper used the current seismic networks in burst-prone coal mines to conduct forward modeling experiments to explore the distribution characteristics of source location error vectors in the mining field. A new method for characterizing seismic fracture connectivity that considers location accuracy impacts was proposed and applied for coal burst pre-warning in a longwall face. The results show that significant vectorial differences of seismic source location accuracy at different area of the mining field is a key factor in false identifying coal burst risks. The proposed Fracture-connectivity-probability Index (\begin{document}$ F{_{{\mathrm{sum}}}} $\end{document}) characterizes the rupture scale by using the near-field radius that relates to the seismic energy level, which considers the locating error impacts on fracture connectivity between seismic sources at different distances. \begin{document}$ F{_{{\mathrm{sum}}}} $\end{document} can restore the distribution law of the fracture extension and connectivity probabilities of the coal-rock mass in the greatest extent, and it also corresponds well to the coal burst risks. \begin{document}$ F{_{{\mathrm{sum}}}} $\end{document} can balance forecast accuracy and recall rate and have better correlation with coal burst, which can be an ideal indicator for periodical coal burst risk assessment. The outcome of this research can provide references for evaluating the monitoring capability of seismic networks and improving the ability and efficiency of coal burst pre-warning and prevention.